Process for producing aromatic compounds by friedel-crafts reaction

ABSTRACT

There is provided a process for producing an aromatic compound by Friedel-Crafts reaction product, which comprises reacting an aromatic compound with an ester compound in the presence of a heteropolyacid-containing solid acid catalyst.

CROSS-REFERENCES TO RELATED APPLICATIONS

The application is an application filed under 35 U.S.C. §111 (a)claiming pursuant to 35 U.S.C. §119 (e) of the filing date ofProvisional Application 60/386,744 on Jun. 10, 2002, pursuant to 35 US.C. §111 (b).

FIELD OF THE INVENTION

The present invention relates to a process for producing aromaticketones, aromatic carboxylic acids, aromatic alcohols, and alkylated oralkenylated aromatics by the Friedel-Crafts reaction of an aromaticcompound and an ester compound in the presence of aheteropolyacid-containing solid acid catalyst. Aromatic compounds byFriedel-Crafts reaction such as aromatic ketones, aromatic carboxylicacids, aromatic alcohols, and alkylated or alkenylated aromatics areindustrially useful compounds and are widely used as raw materials formedicaments, raw materials for pesticides, electronic materials, and rawmaterials for functional resins.

BACKGROUND OF THE INVENTION

Processes for producing Friedel-Crafts reaction products and catalyststhereof are described in many literatures. For example, Hendrickson,Cram, Hammond “ORGANIC CHEMISTRY” (third edition), page 668-683(1970)describes that an aromatic compound is alkylated or acylated by theFriedel-Crafts reaction. The literature includes an example in whichalkyl halide, olefin, alcohol and p-toluenesulfonylated alkane arealkylated in the presence of aluminum chloride and concentrated sulfuricacid. It also describes that an aromatic compound is acylated byaluminum chloride, boron trifluoride, hydrogen fluoride, phosphoric acidand sulfuric acid using acid halide or acid anhydride as an acylatingagent. It also describes that the Fries rearrangement proceeds byaluminum chloride and the Hoesch reaction proceeds by zinc chloride as asimilar example of the Friedel-Crafts reaction in view of a reactionmechanism.

The processes of synthesizing indanone, which is useful as raw materialsfor medicaments, include, but are not limited to, a process whereincinnamic acid is synthesized by the Perkin reaction of benzaldehyde andthe resulting cinnamic acid is reduced with hydrogen to formphenylpropionic acid, which is further converted into indanone by theintramolecular acylation reaction, and a process as shown in thefollowing reaction scheme 1, wherein acrylic acid is reacted withthionyl chloride to form acid chloride, and the resultant acid chlorideis reacted with benzene in the presence of large amounts of aluminiumchloride to prepare indanone.

As shown in the following reaction scheme 2, tetralone is obtained inthe similar manner. For example, benzene is reacted with succinicanhydride using an aluminum chloride reagent to form a phenylketobutyricacid, which is reduced with hydrogen to obtain phenylbutyric acid, andthen tetralone is obtained by intramolecular acylation of phenylbutyricacid using an aluminum chloride reagent.

All of the processes as mentioned above require a plurality of reactionsteps and are complicated. In addition, aluminium chloride, thionylchloride, acid chloride, and the like, are fuming, errosive, andpoisonous, and therefore a care must be taken in handling thesesubstances.

C. De Castro et al., J. Molecular Catal., 134, (1998) 215-222 hasreported that an indanone derivative is produced from crotonic acid andm-xylene as raw materials using a 60% phosphorus-tungsten-carryingcatalyst. However, TON (the number of products per number of catalyticactive sites) is very low such as 3.5 and an improvement is required inview of the synthesis.

Similarly, as the process of synthesizing an alkylcarboxylic acidcontaining trimethylbenzene, there is proposed a process of synthesizingthe alkylcarboxylic acid by converting aldehyde of trimethylbenzene intoketocarboxylic acid by means of the Perkin reaction and reducing theresulting ketocarboxylic acid with hydrogen.

E. F. Kozhevnikova et al., Chem. Comm, 2002, (11), 1178-1179 hasreported a similar reaction by means of the Fries rearrangementreaction.

As described in the prior art, zinc chloride including aluminum chlorideis required as a reagent for promoting the Friedel-Crafts reaction and apolar solvent such as nitromethane or nitrobenzene is commonly used todissolve the chloride. In addition to aluminum chloride, mineral acidssuch as boron trifluoride, hydrogen fluoride, phosphoric acid andsulfuric acid as well as trifluorosulfonic acid have been used.

These reagents often caused a problem in the post-treatment steps suchas purification and separation after the reaction. For example, uponseparation and recovering when using aluminum chloride, aluminumchloride is hydrolyzed to produce a large amount of wastes. In case ofrecovering the product, it is often difficult to separate the aqueouslayer and the organic layer of an aluminum chloride hydrolysis solution.Because of evolution of a large amount of a hydrochloric acid gas, thematerial of the reactor requires acid resistance and a high-qualitymaterial must be used.

Therefore, the present invention provides a means for solving manyproblems described above. By providing a process for producing anaromatic compound by Friedel-Crafts reaction by reacting an aromaticcompound with an ester compound in the presence of aheteropolyacid-containing solid acid catalyst, it is made possible toprovide an environmentally friendly and economical process, whichreplaces the reaction reagent by a catalyst, thereby to preventproduction of a large amount of wastes, facilitates separation andrecovering of the catalyst, and sometimes enables reuse of the catalystand eliminates the use of a reactor made of a high-quality material.

As described above, a conventional process of synthesizing indanone,tetralone and alkane having a trimethylphenyl group requires a largenumber of the reaction processes and was inferior in economicalefficiency taking account of equipment cost, labor cost, utilities costand waste disposal cost. The process of C.De Castro et al. is anepoch-making process for synthesizing indanone, but is insufficient inTON which exhibits catalytic performances, and the process does notdescribe sufficient information with respect to separation and reuse ofthe catalyst.

SUMMARY OF THE INVENTION

To achieve the object described above, the present inventors haveintensively studied and found that the objective aromatic compound byFriedel-Crafts reaction can be obtained with high yield by reacting anaromatic compound with an ester compound in the presence of aheteropolyacid-containing solid acid catalyst, and thus they havecompleted the present invention including:

-   -   [1] A process for producing an aromatic compound by        Friedel-Crafts reaction product, which comprises reacting an        aromatic compound with an ester compound in the presence of a        heteropolyacid-containing solid acid catalyst;    -   [2] The process according to [1], wherein the        heteropolyacid-containing solid acid catalyst is a solid acid        catalyst comprising a carrier and a heteropolyacid carried on        the carrier;    -   [3] The process according to [1] or [2], wherein a central atom        of the heteropolyacid is selected from the group consisting of        P, Si, B, Ge and As and a coordinating atom comprises at least        one of Mo and W;    -   [4] The process according to [1] or [2], wherein a central atom        of the heteropolyacid is selected from the group consisting of        Si and Ge and a coordinating atom comprises at least one of Mo        and W;    -   [5] The process according to [1], wherein an amount of the        heteropolyacid carried in the heteropolyacid-containing solid        acid catalyst is 50% by weight or less;    -   [6] The process according to [1], wherein an amount of the        heteropolyacid carried in the heteropolyacid-containing solid        acid catalyst is 30% by weight or less;    -   [7] The process according to [2], wherein a relative surface        area of the carrier supporting the heteropolyacid is 20 m²/g or        more;    -   [8] The process according to [2], wherein the carrier carrying        the heteropolyacid has a purity of 98% or higher;    -   [9] The process according to [1], wherein the ester compound        comprises lactones;    -   [10] The process according to [1], wherein the aromatic compound        by Friedel-Crafts reaction comprises aromatic ketones, aromatic        carboxylic acids, aromatic alcohols, or alkylated or alkenylated        aromatics;    -   [11] The process according to [10], wherein the aromatic        compound by Friedel-Crafts reaction is aromatic ketones or        aromatic carboxylic acids;    -   [12] The process according to [11], wherein the aromatic        compound by Friedel-Crafts is aromatic ketones;    -   [13] The process according to [1], wherein the Friedel-Crafts        reaction product is cyclized ketones;    -   [14] The process according to [1], comprising the step of        reusing the heteropolyacid-containing solid acid catalyst after        separating and recovering it;    -   [15] The process according to [14], wherein the catalyst is        regenerated in the step of reusing the heteropolyacid-containing        solid acid catalyst after separating and recovering it; and    -   [16] An aromatic compound by Friedel-Crafts reaction, produced        by the production process of any one of [1] to [15].

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described.

The aromatic compound in the present invention as a raw material(hereinafter also referred to as simply “aromatic compound”) is anextended aromatic compound which is composed of an aromatic ring orheterocycle having at least one moiety which undergoes theFriedel-Crafts reaction, and also includes a hydrocarbon-type aromaticcompound such as benzene or naphthalene, a non-benzene-type aromaticcompound such as cyclopentadiene or cycloheptatriene, and a heterocycliccompound such as pyridine, pyrrole or tetrahydrofuran. Those having asubstituent such as alkyl group, hydroxyl group, amino group, nitrogroup, alkoxy group, acetyl group or halogen are also included.

The aromatic compound in the present invention will now be described.

Typical examples of the hydrocarbon-type aromatic compound such asbenzene or naphthalene in the present invention include benzene,naphthalene, anthracene, phenanthrene, diphenylmethane, biphenyl,biphenyl ether and fluorene. The non-benzene-type aromatic compound alsoincludes cyclopentadiene, cycloheptatriene, and a compound condensedthereto. Typical examples thereof include indan. A heterocyclic compoundsuch as pyridine, pyrrole, tetrahydrofuran or thiophene can also belisted.

Examples of the substituent bonded to an aromatic compound skeleton inthe present invention include, but are not limited to, alkyl group,hydroxyl group, amino group, nitro group, alkoxy group, acetyl group,halogen, and group having halogen.

Examples of the aromatic compound having an alkyl substituent includecompound having an alkyl substituent on the benzene ring, such astoluene, o-xylene, m-xylene, p-xylene, mesitylene,1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene,1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene,1,2,4,5-tetramethylbenzene, ethylbenzene, n-propylbenzene, cumene,n-butylbenzene, isobutylbenzene, or t-butylbenzene; compound having amethyl group on the naphthalene ring, such as 1-methylnaphthalene,2-methylnaphthalene, 1,2-dimethylnaphthalene, 2,3-dimethylnaphthalene,1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene,2,6-dimethylnaphthalene, 1,2,3-trimethylnaphthalene,1,6,7-trimethylnaphthalene, 2,6,7-trimethylnaphthalene,1,4,5-trimethylnaphthalene, 1,4,6-trimethylnaphthalene,2,3,5-trimethylnaphthalene, 2,3,6-trimethylnaphthalene,1,4,5,8-tetramethylnaphthalene, or 2,3,6,7-tetramethylnaphthalene;compound having an alkyl substituent on the anthracene ring; compoundhaving an alkyl substituent on the phenanthrene ring; compound having analkyl substituent on the benzene ring of diphenylmethane; compoundhaving an alkyl substituent on the benzene ring of biphenyl; compoundhaving an alkyl substituent on the benzene ring of biphenyl ether;compound having an alkyl substituent on the fluorene ring; and compoundhaving an alkyl substituent on the indene ring.

A compound having a halogen substituent, an alkoxy substituent, ahydroxyl group, an amino group, a nitro group or an acetyl group on thearomatic ring is also included in the aromatic compound having asubstituent. Examples thereof include chlorobenzene, chlorotoluenes,chloroxylenes, bromotoluenes, bromoxylenes, anisole, veratole,methoxytoluenes, methoxyxylenes, phenols, anilines, nitrobenzenes, andmethyl phenyl ketones.

Examples of the non-benzene-type aromatic compound includecyclopentadiene, methylcyclopentadiene, dimethylcyclopentadiene,cycloheptatriene, methylcycloheptatriene, and a compound condensedthereto, such as indan or methylindan.

The heterocyclic compound in the present invention is a compound havinga ring formed of two or more kinds of atoms. Examples thereof includepyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole,3-pyrrolinepyrrolidine, pyridine, pyrimidine, purine, quinoline,isoquinoline, carbazole, indole, and benzofuran. The heterocycliccompound having a substituent may have an alkyl substituent, a halogensubstituent, an alkoxy substituent, a hydroxyl group, an amino group, anitro group or an acetyl group on the ring of the heterocyclic compound.Examples thereof include methylpyrrole, ethylpyrrole, propylpyrrole,methylfuran, ethylfuran, propylfuran, methylthiophene, ethylthiophene,propylthiophene, methylimidazole, ethylimidazole, propylimidazole,methyloxazole, ethyloxazole, propyloxazole, methylthiazole,ethylthiazole, propylthiazole, methylpyrazole, ethylpyrazole,propylpyrazole, methyl-3-pyrrolinepyrrolidine,ethyl-3-pyrrolinepyrrolidine, propyl-3-pyrrolinepyrrolidine, picoline,ethylpyridine, propylpyridine, methylpyrimidine, ethylpyrimidine,propylpyrimidine, methylpurine, ethylpurine, propylpurine,methylquinoline, ethylquinoline, propylquinoline, methylisoquinoline,ethylisoquinoline, propylisoquinoline, methylcarbazole, ethylcarbazole,propylcarbazole, methylindole, ethylindole, propylindole,methylbenzofuran, ethylbenzofuran, propylbenzofuran, methoxyfuran, furanchloride, benzofuran chloride, benzothiophene chloride,acetoaminopyrrole, nitropyrrole, nitrobenzofuran, acetoxyfuran,acetoxypyrrole, nitroindole, dimethylaminoindole, dimethylindole,N-acyldimethylindole, methylbenzofuran chloride, thiophenoxyfuran, andphenoxypyrrole.

The aromatic compound in the present invention is preferably ahydrocarbon-type aromatic compound such as benzene or naphthalene, or anon-benzene-type aromatic compound. More preferably, it is ahydrocarbon-type aromatic compound having an alkyl substituent, such asbenzene or naphthalene and examples thereof include toluene, xylene,trimethylbenzene, and methylnaphthalene. An alkyl benzene-typehydrocarbon-type aromatic compound is more preferred.

These aromatic compounds can be used as such as far as they are generalindustrial grade compounds. Preferably, these aromatic compounds areused after purifying so as to meet the standard of the resultingproduct. The purification process may be any processes, which are wellknown to a person with an ordinary skill in the art, such asdistillation, recrystallization, rinsing, filtration with dissolving,and removal with adsorption.

The ester compound in the present invention is a compound having anester group (—COO—) and refers to lactones as an intramolecularlycyclized ester, an aliphatic or aromatic ester, or a carbonate ester(—OCOO—). Particularly, lactones are preferred. Examples thereof includeβ-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone,γ-valerolactone, γ-caprolactone, γ-caprylolactone, γ-laurolactone,crotolactone, α-angelicalactone, β-angelicalactone, δ-caprolactone,tetronic acid, α-pyrone, β-pyrone, phthalide, coumarin, and macrocycliclactone.

The aromatic compound by Friedel-Crafts reaction produced in the presentinvention (hereinafter also referred to as “Friedel-Crafts reactionproduct) includes aromatic ketones, aromatic carboxylic acids, aromaticalcohols, and alkylated or alkenylated aromatics. The present inventionis suitable for use in the process for producing aromatic ketones andaromatic carboxylic acids as the Friedel-Crafts reaction product. Thepresent invention is suitable more preferably for use in the process forproducing aromatic ketones as the Friedel-Crafts reaction product. Thepresent invention is suitable for use in the process for producingclyclized ketones as the Friedel-Crafts reaction product among thearomatic ketones. The present invention is most suitable for used in theprocess for producing indanones and tetralones.

According to the process of the invention, as shown in the followingreaction scheme 3, it is made possible to produce tetralone and3-methylindanone in one step by the Friedel-Crafts reaction betweenbenzene and γ-butyrolactone.

The solvent used in the Friedel-Crafts reaction of the present inventionmay be an industrial grade solvent which is not a special high-purityproduct. An aromatic compound as a raw material of the Friedel-Craftsreaction can be used as the solvent. In case the aromatic compound asthe raw material of the Friedel-Crafts reaction and the solvent areseparately used, an aromatic compound for the solvent having reactivitylower than that of the aromatic compound for the raw material must beused.

The catalyst used in the present invention will now be described.

The catalyst in the present invention is a heteropolyacid-containingsolid acid catalyst. The heteropolyacid is defined as a generic name ofan acid produced by condensing two or more kinds of inorganic oxyacids(Kagaku Sosetsu, “Design of Catalysts”, No. 34, 116-141 (1982), GakkaiShuppan Center). Examples of the heteropolyacid-containing solid acidcatalyst include catalyst made only of the heteropolyacid,heteropolyacid-containing catalyst comprising a carrier and a mixturewith the heteropolyacid or the heteropolyacid carried on the carrier,and catalyst containing the heteropolyacid entrapped therein. Amongthese catalysts, a catalyst comprising a carrier and the heteropolyacidcarried on the carrier is preferred.

The heteropolyacid in the present invention is preferably aheteropolyacid wherein a central atom comprises P, Si, B, Ge or As and acoordinating atom comprises Mo or W, or a mixture thereof. Specificexamples thereof include [PM₁₂O₄₀]³⁻, [SiMo₁₂O₄₀]⁴⁻, [GeMo₁₂O₄₀]⁴⁻,[ASMo₁₂O₄₀]³⁻, [PMo₁₁O₃₉]⁷⁻, [ASMo₁₁O₃₉]7−, [SiMo₁₁O₃₉]⁸⁻,[GeMo₁₁O₃₉]⁸⁻, [P₂Mo₁₈O₆₂]⁶⁻, [As₂Mo₁₈O₆₂]⁶⁻, [PW₁₂O₄₀]³⁻, [SiW₁₂O₄₀]⁴⁻,[GeW₁₂O₄₀]⁴⁻, [ASW₁₂O₄₀]³⁻, [PW₁₁O₃₉]⁷⁻, [ASW₁₁O₃₉]⁷⁻, [SiW₁₁O₃₉]⁸⁻,[GeW₁₁O₃₉ ]⁸⁻, [P₂W₁₈O₆₂ ]⁶⁻, and [AS₂W₁₈O₆₂]⁶⁻. Examples of theheteropolyacid wherein the coordinating atom comprises the mixture of Moand W include [SiW₁Mo₁₁O₄₀]⁴⁻, [SiW₂Mo₁₀O₄₀]⁴⁻, [SiW₃Mo₉O₄₀]⁴⁻,[SiW₄Mo₈O₄₀]⁴⁻, and [SiW₁₁Mo₁O₄₀]⁴⁻.

More preferred heteropolyacid is a heteropolyacid wherein the centralatom comprises Si or Ge and the coordinating atom comprises Mo or W, ora mixture thereof.

The counter cation is preferably proton, ammonium salt or alkali metalsalt.

The heteropolyacid in the present invention can be synthesized by aprocess well known in the art. Specifically, the heteropolyacid can beobtained by heating an aqueous acidic solution (pH: about 1 to 2)containing a salt of molybdic acid or tungstic acid and simple oxyacidof a hetero atom or a salt thereof. A commercially available reagent maybe used as such.

Examples of the carrier used in the present invention include silica,activated carbon, and diatomaceous earth (“soil produced as a result ofaccumulation of husk of diatom, pure silicic acid husk comprising 94%SiO₂ and 6% H₂O”, Iwanami Rikagaku Jiten, fifth edition, page 405(1998)). Among these carriers, silica and activated carbon are preferredand high-purity silica is more preferred.

The carrier having higher purity is preferred. The purity of the carrieris preferably 96% or higher, and more preferably 98% or higher. When thecarrier contains a component capable of decomposing the heteropolyacid,sufficient performances can not be exhibited. Alkali metal oxide, alkaliearth metal oxide, alumina, gallium oxide and indium oxide areunfavorable impurities. The purity of the carrier is calculated whilecomponents other than SiO₂ as a main component being considered asimpurities in case of silica and diatomaceous earth, or components otherthan C being considered as impurities in case of activated carbon.

The carrier having smaller particle diameter exhibits catalyticperformances more easily. However, in deciding the particle diameter, itis also necessary to take into account balance between the catalyticperformance and separability of the catalyst from a reaction solutionduring sedimentation or filtration. In general, the carrier is not onlyin the form of primary particles, but also in the form of an aggregateor floc. With respect to the particle size, the carrier including theaggregate preferably has a weight-average particle diameter of 10 μm ormore, more preferably 50 μm or more, and still more preferably 200 μm ormore.

The particle size distribution is preferably narrow to some extent inthe preparation of the catalyst. Since the carrier is likely to beformed into powders while stirring, the carrier preferably hassufficient mechanical strength.

The carrier is preferably a porous carrier including pores having adiameter of 1 nm or more. The narrower pore size distribution exhibitscatalytic performances more easily after supporting. The pore volume ispreferably 0.1 ml/g or more, and more preferably 0.2 ml/g or more.

The relative surface area of the carrier preferably 10 m²/g or more, andmore preferably 20 m²/g or more. Silica and diatomaceous earthpreferably has a relative surface area of 20 m²/g or more, whileactivated carbon preferably has a relative surface area of 500 m²/g ormore. The relative surface area is a value as measured by a BET processusing a nitrogen gas and the measuring process is described, forexample, in “Shokubai Koza 3 (Catalyst Lecture 3), Characterization ofSolid Catalyst”, pages 204-5 (1985), Kodansha Scientific.

The carrier is preferably subjected to a pre-treatment. Acid cleaning ispreferably conducted when the carrier includes a large amount ofimpurities. When using silica, it is preferably sintered between 400° C.and 800° C.

As the process of carrying the heteropolyacid on the carrier, animpregnation process (comprising impregnating the whole carrier with aheteropolyacid solution according to the volume of the carrier) isgenerally used. A dipping process (comprising dipping the carrier in anexcess amount of a heteropolyacid solution and swishing theheteropolyacid solution off, thereby carrying the heteropolyacidabsorbed in the carrier) can also be used.

The amount (rate) of the heteropolyacid carried is calculated by thefollowing equation.Supporting amount=[(weight of heteropolyacid)/((weight ofheteropolyacid)+weight of carrier)]*100The heteropolyacid carrying amount is preferably 50% by weight or less,and more preferably 30% by weight or less. Too large carrying amountmakes it impossible to sufficiently exhibit the function of theheteropolyacid, resulting in poor economy. Also too small carryingamount makes it impossible to sufficiently exhibit the function.

After carrying the heteropolyacid, the carrier is dried at thetemperature at which the heteropolyacid is not decomposed. Thetemperature is preferably 300° C. or lower, and more preferably 280° C.or lower. The drying times may be preferably several times, and morepreferably 4 hours or more. It is preferred to dry in a clean air flow.

The dried heteropolyacid-carrying catalyst is preferably stored in adried state. The dried heteropolyacid-carrying catalyst is preferablyremoved from the dryer immediately after drying and then put in a sealedcontainer covered with a desiccating agent so that the catalyst hardlyabsorbs moisture.

The heteropolyacid-carrying catalyst of the present invention ispreferably activated before use in the Friedel-Crafts reaction. Thecatalyst may be activated by treating at the same temperature as thedrying temperature for the same time. Although it depends on the storagemethod, performances of the catalyst are likely to be changed byre-adsorption of moisture during the storage. This is because, it ispresumed that the catalyst returns to the state suited for the objectivereaction in the present invention.

The process for producing a Friedel-Crafts reaction product by reactingan aromatic compound with an ester compound in the presence of the solidacid catalyst prepared by the above process will now be described.

A molar ratio of the ester compound to the aromatic compound ispreferably from 1 to 400, more preferably from 3 to 300, and still morepreferably from 5 to 200.

A molar ratio of the ester compound to the heteropolyacid-carrying solidacid catalyst is preferably 5:1 or less, and more preferably 10:1 orless.

The sequence of the aromatic compound, the ester group-containingcompound, the catalyst and the solvent to be charged does not exerts alarge influence on the reaction results. However, these components arepreferably mixed and reacted before the temperature of the mixtureraises to the reaction temperature. If possible, it is preferred tosufficiently mix them at room temperature.

Although the reaction temperature and the reaction pressure of theFriedel-Crafts reaction of the present invention vary because they areinfluenced by the kinds of the aromatic compound and the ester compound,the reaction temperature is preferably between 150° C. and 250° C. Thereaction can be conducted at normal pressure, or under pressure orreduced pressure, but is preferably conducted under a pressure within arange from normal pressure to 500 kPa (gauge pressure).

The heating rate during the reaction is important. According to the kindof the ester compound, polymerization of the ester compound often occurswithout conducting proper Friedel-Crafts reaction. The polymerizationoften occurs at the temperature lower than the temperature at whichproper Friedel-Crafts reaction occurs. Therefore, it is preferred toraise to the desired reaction temperature by increasing the heating rateas high as possible.

The reaction time must be optimized by the molar ratio of the aromaticcompound to the ester compound and the reaction conditions. For example,when the reaction is conducted for too long time, the valuable objectivecompound is sometimes decomposed. It is important to synthesize byoptimizing the reaction conditions without being decomposed.

The reaction is preferably conducted in a reaction atmosphere afterremoving oxygen and moisture as much as possible. In case the reactionis conducted in an autoclave, the reaction is preferably initiated afterthe atmosphere in the autoclave is replaced by an inert gas (forexample, nitrogen, argon, or helium).

Separation, recovering and reuse of the heteropolyacid-containing solidacid catalyst will now be described.

In case the catalyst sediments while standing after the completion ofthe reaction, the supernatant is drawn and the catalyst proceeds to thepurification step of the product. The catalyst separated and recoveredcan also be reused as such. As a matter of course, in case of thecatalyst which can not be separated, there can be used a separationprocess (for example, centrifugation, or filtration) which can becarried out by a person with an ordinary skill in the art.

In the step of separating, recovering and reusing theheteropolyacid-containing solid acid catalyst, the process for producingthe Friedel-Crafts reaction product including regeneration of thecatalyst will now be described.

The catalyst regeneration process includes cleaning with an organicsolvent. In this case, cleaning with heating is preferred. The cleaningsolvent is preferably a solvent such as hydrocarbon-type hexane,heptane, or methylene chloride. After the filtration, the catalyst issufficiently dried at about 100° C. Thereafter, the resulting catalystcan be used again as the catalyst.

A batch-wise reactor is used, commonly, and also a liquid-phase flowsystem or a catalyst fixed bed of the liquid-phase flow system can beused.

Although the material of the reactor varies depending on the kind of rawmaterials and reaction conditions, stainless steel and carbon steel arecommonly used.

The following Examples illustrate the present invention in detail, butare not intended to limit the present invention.

EXAMPLES Example 1 Silica-Carried 10% Tungstosilicic Acid Catalyst,p-xylene

As a heteropolyacid, tungstosilicic acid (special grade chemical, purechemistry: SiO.12WO₃.26H₂O) was used as such without being purified.Silica (Fuji Silicia Q-10, surface area: 270 m²/g, pore diameter: about10 nm, pore volume: 0.82 cc/g, impurities: Na=240 ppm, Al=65 ppm, Ca=130ppm, Ti=100 ppm, total content of impurities=594 ppm, and thereforesilica purity is 99.9% or higher) was used after firing in a mufflefurnace at 500° C. for 5 hours.

The process for producing a catalyst will be described. 6.67 g oftungstosilicic acid was dissolved in 78 ml of pure water and 60 g offired silica was impregnated with the resulting solution. After airdrying, the impregnated silica was dried in a hot-air drying apparatusat 150° C. for 10 hours. The resulting catalyst is referred to as 10 wt% HSiW/SiO₂ catalyst.

In a 300 ml stainless steel autoclave equipped with a stirrer, 100 ml ofp-xylene (799 mmol) and 1 ml of γ-butyrolactone (14.8 mmol) were chargedand 3.20 g of the 10 wt % HSiW/SiO₂ catalyst (0.097 mmol-HSiW) wascharged, and then the autoclave was capped. The autoclave was purgedwith an accumulated high-purity nitrogen gas and this operation wasrepeated 10 times. After confirming the absence of pressure loss, thegas was purged. To accelerate temperature raise, the autoclave wasdipped in a previously heated oil bath and the reaction was initiated.The reaction was conducted at 200° C. for 5 hours. After the completionof the reaction, the supernatant was removed and then analyzed by aninternal standard process using GC (FID, He carrier gas, 30mDB-1column). After the reaction was conducted for 5 hours, the conversionratio of γ-butyrolactone was 64.3%, the yield of 5,8-dimethyltetralonebased on γ-butyrolactone was 39.9% (TON=15), and the yield oftrimethylindanone was 2.6%.

Example 2 Reuse of Catalyst

Using the same reactor as in Example 1, 3.20 g of the 10 wt % HSiW/SiO₂catalyst (0.097 mmol-HSiW) as the catalyst produced in Example 1, 100 mlof p-xylene (799 mmol) and 1 ml of γ-butyrolactone (14.8 mmol) werereacted at 196° C. for 3 hours to obtain 5,8-dimethyltetralone (yieldbased on γ-butyrolactone: 30.4%). After removing the supernatant byfiltration, 100 ml of p-xylene (799 mmol) and 1 ml of γ-butyrolactone(14.8 mmol) as raw materials were charged again and then reacted at 196°C. for 3 hours. As a result, 5,8-dimethyltetralone (yield based onγ-butyrolactone: 23.2%) was obtained. The catalyst could be reused.

Example 3 Reuse and Regeneration of Catalyst

After the completion of the first reaction in Example 1, the supernatantwas removed, the remained catalyst was washed with 100 ml of hexane withstirring at room temperature. The hexane supernatant was removed,followed by drying under reduced pressure at 50° C. 100 ml of p-xylene(799 mmol) and 1 ml of γ-butyrolactone (14.8 mmol) as raw materials werecharged again and then reacted at 196° C. for 3 hours. As a result,5,8-dimethyltetralone (yield based on γ-butyrolactone: 28.7%) wasobtained. The effect of regenerating the catalyst was exerted.

Example 4 Catalyst Carrying No Tungstosilicic Acid, p-xylene

In the same manner as in Example 1, except that the same amount oftungstosilicic acid (0.320 g) was used in the catalyst in place of 3.20g of the 10 wt % HSiW/SiO₂ catalyst (0.097 mmol-HSiW) used in Example 1,the reaction and analysis were conducted. After the reaction wasconducted for 5 hours, the conversion ratio of γ-butyrolactone was 9.0%and the yield of 5,8-dimethyltetralone based on γ-butyrolactone was 2.5.Although the reaction can be conducted even when using the catalystcarrying no tungstosilicic acid, more remarkable effect is exerted usinga tungstosilicic acid-carrying catalyst.

Example 5 Silica-Carried 10% Phosphotungstic Acid Catalyst, D-xylene

In the same manner as in Example 1, except that 2.90 g of asilica-carried phosphotungstic acid catalyst (manufactured by Wako PureChemicals Industries, Ltd., special grade) was used in place of 3.20 gof the 10 wt % HSiW/SiO₂ catalyst (0.097 mmol-HSiW) used in Example 1,the reaction and analysis were conducted. After the reaction wasconducted for 5 hours, the conversion ratio of γ-butyrolactone was 31.7%and the yield of 5,8-dimethyltetralone based on γ-butyrolactone was14.1%. The reaction can be conducted even when using a phosphotungsticacid-carrying catalyst.

Example 6 Silica-Carried 50% Tungstosilicic Acid Catalyst, p-xylene

In the same manner as in Example 1, except that 3.2 g of asilica-carried 50% tungstosilicic acid catalyst was used in place of3.20 g of the 10 wt % HSiW/SiO₂ catalyst (0.097 mmol-HSiW) used inExample 1, the reaction and analysis were conducted. After the reactionwas conducted for 5 hours, the conversion ratio of γ-butyrolactone was100% and the yield of 5,8-dimethyltetralone based on γ-butyrolactone was7.4%. Although the reaction can be conducted even when using a 50%tungstosilicic acid-carrying catalyst, the yield is lowered.

Example 7 Silica-Carried 25% Tungstosilicic Acid Catalyst, p-xylene

In the same manner as in Example 1, except that 1.6 g of asilica-carried 25% tungstosilicic acid catalyst was used in place of3.20 g of the 10 wt % HSiW/SiO₂ catalyst (0.097 mmol-HSiW) used inExample 1 and a half amount of γ-butyrolactone were used and then thereaction was conducted at a reaction temperature of 210° C., thereaction and analysis were conducted. After the reaction was conductedfor 2 hours, the conversion ratio of γ-butyrolactone was 80.8% and theyield of 5,8-dimethyltetralone based on γ-butyrolactone was 67.9%. Theyield was higher when using a 25% tungstosilicic acid-carrying catalyst.

Example 8 Catalyst Produced by Using Silica Carrier Containing 1% byWeight of Al

The silica carrier used in Example 1 was impregnated with aluminumnitrate so that it contains 1% by weight of Al, followed by air dryingand further sintering at 500° C. for 5 hours to produce a 10 wt %HSiW/SiO₂ catalyst in the same manner as in Example 1.

The catalyst thus produced was evaluated in the same manner as inExample 1. As a result, the conversion ratio of γ-butyrolactone was 5.3%and the yield of 5,8-dimethyltetralone based on γ-butyrolactone was2.4%. As a result of the use of the silica carrier containing 1% byweight of Al, the purity of the carrier purity was 98.9% or higher and aremarkable inhibition effect was exerted, however, a product wasobtained.

Example 9 Mesitylene

In the same 100 ml autoclave as in Example 1, 1.5 g of tungstosilicicacid, 40 ml of mesitylene and 2.55 ml of γ-butyrolactone were chargedand reacted at 180° C. for 6 hours, and then analysis was conducted. Asa result, the conversion ratio of γ-butyrolactone was 85.1% and2,4,6-trimethylphenylbutyric acid (yield based on γ-butyrolactone:33.5%) was obtained.

Result

The use of the production process of the present invention makes itpossible to synthesize tetralones and indanones in one step reaction,easily recover a catalyst and reuse the catalyst. The present inventionexerts large effects such as reduction of wastes, simplification of theseparation step and elimination of the use of a reactor made of ahigh-quality material.

1. A process for producing an aromatic compound by Friedel-Crafts reaction, which comprises reacting an aromatic compound with an ester compound in the presence of a heteropolyacid-containing solid acid catalyst.
 2. The process according to claim 1, wherein the heteropolyacid-containing solid acid catalyst is a solid acid catalyst comprising a carrier and a heteropolyacid carried on the carrier.
 3. The process according to claim 1, wherein a central atom of the heteropolyacid is selected from the group consisting of P, Si, B, Ge and As and a coordinating atom comprises at least one of Mo and W.
 4. The process according to claim 1, wherein a central atom of the heteropolyacid is selected from the group consisting of Si and Ge and a coordinating atom comprises at least one of Mo and W.
 5. The process product according to claim 1, wherein an amount of the heteropolyacid carried in the heteropolyacid-containing solid acid catalyst is 50% by weight or less.
 6. The process according to claim 1, wherein an amount of the heteropolyacid carried in the heteropolyacid-containing solid acid catalyst is 30% by weight or less.
 7. The process according to claim 2, wherein a relative surface area of the carrier supporting the heteropolyacid is 20 m² μg or more.
 8. The process according to claim 2, wherein the carrier carrying the heteropolyacid has a purity of 98% or higher.
 9. The process according to claim 1, wherein the ester compound comprises lactones.
 10. The process according to claim 1, wherein the aromatic compound by Friedel-Crafts reaction comprises aromatic ketones, aromatic carboxylic acids, aromatic alcohols, or alkylated or alkenylated aromatics.
 11. The process according to claim 10, wherein the aromatic compound by Friedel-Crafts reaction is aromatic ketones or aromatic carboxylic acids.
 12. The process according to claim 11, wherein the aromatic compound by Friedel-Crafts is aromatic ketones.
 13. The process according to claim 1, wherein the Friedel-Crafts reaction product is cyclized ketones.
 14. The process according to claim 1, comprising the step of reusing the heteropolyacid-containing solid acid catalyst after separating and recovering it.
 15. The process according to claim 14, wherein the catalyst is regenerated in the step of reusing the heteropolyacid-containing solid acid catalyst after separating and recovering it.
 16. An aromatic compound by Friedel-Crafts reaction, produced by the production process of claim
 1. 